"He was always thinking of other people. His sort doesn't come along very often and we're going to miss him terribly. A fine, fine, fine man," said Caldwell.

Dingle was also the father of six children, four of whom he and his wife had adopted, said Caldwell. On top of that, Dingle worked as an on-call rescuer who would "drop everything" and respond with rescue crews at the site of collapsed or burning buildings, Caldwell said.

He laughed when told of Dingle's final act of selflessness -- organ and tissue donation.

"It's just like him. God bless him, I don't doubt that at all -- it's just right in line with his life. He was always thinking of others," said Caldwell. "He was just 37 years old. I don't understand it."

Lee Dingle (L) was killed when a wave slammed him into the sand while he was at the beach with three of his children. (GoFundMe)

Currently, there are more than 113,000 people on waiting lists for organ transplant, according to Joel Newman, senior communications strategist for the United Network for Organ Sharing (UNOS), which manages the organ transplant system in the United States.

That number applies only to patients waiting for organs that are tracked by UNOS, such as hearts, livers, kidneys and lungs. Additional patients who need tissue donations such as corneas are not included in that number, explained Newman.

For an organ donation to occur, a death has to be declared in a hospital setting, though a tissue donation is also possible as long as recovery is made within 24 hours of death, he said.

The organs that UNOS manages are vascular organs that depend on blood supply.

"The moment that circulation ends those organs become unusable," said Newman. Tissues, corneas, heart valves, skin and bone are not so dependent on blood flow and so can be recovered.

"Certainly, any organ donation is greatly needed and is a selfless act," said Newman.

A GoFundMe page set up for the Dingle family had raised more than US$174,000 by Monday afternoon.